1. Field of the Invention
The present invention relates to an electromagnetic contactor having an abrasion preventing means, and more particularly, to an electromagnetic contactor having a means for preventing an sliding portion of a cross bar within the electromagnetic contactor, which is mainly used for opening or closing a motor circuit, from being abraded.
2. Description of the Related Art
In general, an electromagnetic contactor or electromagnetic switch is most generally used when electrically connecting or disconnecting between a power source and a load. The contactor connects or disconnects between two fixed electrodes spatially separated from each other through a moving electrode, in which the force of an electromagnet is used when connecting to each other and the elastic force of a spring or the like is used when disconnecting from each other.
For such a conventional electromagnetic contactor, a cross bar is slidably provided within an upper frame and a lower frame thereof, and an electromotive force is applied to an excitation coil adjacent to a fixed core to magnetize the fixed core, and then a magnetic force generated by the magnetization is applied to pull a movable core mounted on the cross bar to a side of the fixed core, thereby sliding the cross bar. Due to that, it is configured in such a manner that a fixed contact point being fixed and provided at the upper frame is contacted or separated with respect to a movable contact point provided at the cross bar based on a sliding movement of the cross bar, thereby opening or closing a circuit connected to the fixed contact point.
On the other hand, the electromagnetic contactor should have a predetermined insulation as well as should withstand high-temperature heat generated therewithin during the operation. Accordingly, the cross bar and upper/lower frames are formed by using a thermosetting resin.
However, such a thermosetting resin has a relatively high rigidity, thereby easily causing an abrasion when continuously rubbing against each other as described above. In other words, in the electromagnetic contactor, the cross bar continuously repeats to make a sliding movement during the operation and thus a sliding portion of the cross bar may be gradually worn out due to friction during the process. If the abrasion is accumulated, then the sliding movement of the cross bar may be deteriorated, and therefore a contact between the fixed contact point and the movable contact point may be deteriorated, thereby decreasing the reliability of the equipment. Moreover, due to abrasion, dust is generated within the upper and lower frames and it may be a cause of the contact failure and burning damage, thereby reducing the life of the equipment.